The invention concerns mounting a transmission in the rear region of a passenger vehicle, on one side on a rear axle carrier, and on the other side at an additional connecting point on the floor panel structure of the vehicle body with the interposition of elastic bearings. In regard to the prior art, reference is made to EP 0 170 220 A1 and DE 10 2004 004 417 A1.
In EP 0 170 220 A1 there is shown a semitrailing-arm axle's simple rear axle carrier consisting essentially only of a transverse member on which a transmission or a so-called differential housing is mounted. The mounting is by its input side while the output side of this transmission or differential housing, in whose area the drive shafts leading to the driven vehicle wheels are flange-mounted on the two transmission outputs, is fastened via an independent transmission carrier to the floor panel of the vehicle.
On passenger vehicles popular today with more complicated axle constructions, in particular comprising several (individual) wheel control arms per wheel, a transmission is, in so far as present, customarily elastically mounted at three points of an approximately rectangular, frame-shaped rear axle carrier to which most of the wheel control arms are fastened. The frame-shaped rear axle carrier is constructed of two longitudinal and two transverse members. Via this elastic mounting of the transmission in the rear axle carrier in connection with the also elastic mounting of the rear axle carrier on the floor panel structure of the vehicle body, vehicle body longitudinal members or the like introduced therein also counting as such, one avoids an undesirable introduction of high-frequency vibrations which come from the toothing of the transmission into the vehicle body. If on the contrary such high-frequency vibrations are imparted to the vehicle body, e.g. via a defective elastic bearing in the vehicle body, then these vibrations become noticeable as the dreaded “singing” of the transmission, where due to the vehicle body acting as a resonance body this sound becomes disturbingly audible to the occupants of the vehicle.
Basically, the last-described, current structure has proven itself but such an approximately rectangular, frame-shaped rear axle carrier requires a relatively large installation space and restricts the usable space in the area of the rear axle of a passenger vehicle.
To disclose a rear axle carrier more favorable relative to this and, adapted to such a more favorable rear axle carrier, an advantageous mounting of a transmission is the object of the present invention.
The achievement of this object is characterized in that the transmission is mounted on the output side on the sole transverse member of the rear axle carrier, which furthermore comprises two longitudinal members, and on the input side is fastened to the floor panel structure via a serial connection of two elastic bearings with a mass body lying therebetween. Preferably, the transmission is fastened to the floor panel structure at two connecting points which lie side-by-side essentially in the transverse direction of the vehicle, where for the connecting points two such serial connections of elastic bearings are provided with a common mass body. Preferably, the weight of the mass body ranges from 3 kilograms to 7 kilograms.
On the one hand, in the present invention a rear axle carrier is provided which, along with two longitudinal members aligned essentially in the longitudinal direction of the vehicle, now has a single transverse member running essentially in the transverse direction of the vehicle connecting the two longitudinal members to one another and fastened to them. The single transverse member is used instead of the previously customary two transverse members parallel to one another. With the omission of the, or a, second transverse member, there is now provided in this area additional free space which, according to the invention, has a particularly advantageous effect in the area of an input side of a transmission. This is because this available space is able to be used in an optimal manner as storage space or for expanding the interior of the vehicle. Accordingly, a rear axle carrier according to the invention only comprises a single, viewed in the direction of motion, preferably rear transverse member on which the transmission on the output side, i.e. in the area of its transmission outputs, is suspended. On the input side, i.e. in the area of the input of the Cardan shaft coming from the drive assembly disposed in the front area of the vehicle, the transmission is mounted according to the invention directly on the floor panel structure of the vehicle body. The two longitudinal members extend, viewed in the transverse direction of the vehicle, preferably over this mounting area and to the front in the direction of motion of the vehicle. But along with this, deviating from the prior art, here the two longitudinal members are not connected to one another by an (additional) transverse member. Thus there are, as concerns the accordingly configured rear axle carrier, with its two longitudinal members, further adequate possibilities for fastening wheel control arms. The additional free space provided by the omission of a transverse member is particularly large when one omits the transverse member further removed from the transmission's drive shafts leading to the vehicle wheels to be driven. As a rule, that is the rear axle carrier's front transverse member, as viewed in the direction of motion. As the single transverse member of a rear axle carrier according to the invention, the one near to the drive shafts of the transmission remains so that this transmission on its output side continues in a proven manner to be able to be mounted on, or fastened to, this transverse member and therefore on the rear axle carrier.
On the input side, i.e. in the flange area of the Cardan shaft, the transmission is then, for lack of a transverse member, fastened to the floor panel structure of the vehicle body. In order to prevent higher-frequency vibrations emitted by the transmission or its toothing from reaching into the vehicle body via this fastening, a serial connection of two elastic bearings with a mass body lying between these bearings is provided according to the invention. This mass body is therefore mounted, both with respect to the vehicle body or its floor panel structure and to the transmission, elastically, i.e. with interposition or inclusion of rubber layer elements. And, the mass body is designed with the aim of selectively including a mass which has or produces a weight lying in a certain higher range between the housing of the transmission and its suspension on the vehicle body. It is as a function of the value of the critical higher-frequency vibrations of the transmission, which customarily lie in the range 400-600 Hertz, that this weight is chosen, preferably being able to lie in the range from 3 to 7 kilograms.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.